Seamless Control Strategy and Hybrid Module Architecture of Wide Power Range Inverter

Efficient and simple modulation of output power is demanding for radio frequency plasma and wireless power transmission,magnetic resonance imaging systems. In this article, a power modulation strategy that can improve the linearity, power capability and efficiency simultaneously is proposed. The control modes of on/off and Outphasing are combined to ensure shallow phase depth in a wide power range. Hybrid modules composed of load independent class Φ2 structure and symmetrical class Φ2 structures are adopted as on/off modules and PS module to match the proposed control scheme, which are able to provide constant output voltage while remaining zero voltage switching (ZVS) state under resistive-inductive and resistive-capacitive load separately. The on/off module is uniquely designed to behave as a static load when turned off. With the cooperation of control strategy and circuit architecture, the proposed system is able to regulate power linearly with optimal efficiency and minimal voltage and current stress. An implementation with four modules, 13.56 MHz, 25-200 W inverter system is demonstrated, the output power can be seamlessly and linearly controlled with efficiency always within 82%-93.5%. The heat dissipation in prototype is uniform, and is feasible to expand to a higher power compared with other control and circuit structures.